title: Widespread dissemination of aminoglycoside resistance genes armA and rmtB in Klebsiella pneumoniae isolates in Taiwan producing CTX-M-type extended-spectrum beta-lactamases.
abstract: Among 235 extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL) isolates collected from a nationwide surveillance performed in Taiwan, 102 (43.4%) were resistant to amikacin. Ninety-two of these 102 (90.2%) isolates were carrying CTX-M-type beta-lactamases individually or concomitantly with SHV-type or CMY-2 beta-lactamases. The armA and rmtB alleles were individually detected in 44 and 37 of these 92 isolates, respectively. One isolate contained both armA and rmtB. The coexistence of the aac(6')-Il and rmtB genes was detected in three isolates. CTX-M-type beta-lactamase genes belonging to either group 1 (CTX-M-3 and CTX-M-15) or group 9 (CTX-M-14) were found in all armA- or rmtB-bearing ESBL-producing K. pneumoniae isolates, and all were conjugatively transferable. All except one of the isolates bearing armA produced CTX-M enzymes of group 1, and the remaining isolate bearing armA produced a group 9 CTX-M-type beta-lactamase. On the contrary, in the majority of rmtB carriers, the CTX-M-type beta-lactamase belonged to group 9 (62.2%). Molecular typing revealed that the amikacin-resistant ESBL-producing K. pneumoniae isolates were epidemiologically unrelated, indicating that the acquisition of resistance was not through the spread of a resistant clone or a resistance plasmid. A tandem repeat or multiple copies of bla(CTX-M-3) were found in some armA-bearing isolates. An ISEcp1 insert was found in all CTX-M ESBL-producing K. pneumoniae isolates carrying armA or rmtB. In conclusion, the concomitant presence of a 16S rRNA methylase gene (armA or rmtB) and bla(CTX-M) among amikacin-resistant ESBL-producing K. pneumoniae isolates is widespread in Taiwan.
authors.affiliation: Division of Clinical Research, National Health Research Institutes, Zhunan Town, Miaoli County, Taiwan.
authors.forename: Ling
authors.initials: L
authors.lastname: Ma
authors.forename: Chi-Jan
authors.initials: CJ
authors.lastname: Lin
authors.forename: Jiun-Han
authors.initials: JH
authors.lastname: Chen
authors.forename: Chang-Phone
authors.initials: CP
authors.lastname: Fung
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
authors.forename: Yiu-Kay
authors.initials: YK
authors.lastname: Lai
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.forename: L K
authors.initials: LK
authors.lastname: Siu
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000235:genetics / Q000502:physiology; D016521:Electrophoresis, Gel, Pulsed-Field; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D013624:Taiwan; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D001618:beta-Lactamases